fix(harness-claude-code): isolate subagent step tracking (#18631)
Sole Author: Patrick Ribbsaeter (@patrickswedish) · Immutable Commit SHA: 2db9e370e66b56e7802b30e7ea359d9dc9e27209
TypeScript streaming state-machine fix isolating nested parent_tool_use_id subagent events from parent step lifecycle boundaries in Vercel AI SDK's Claude Code harness.
PR #18631
ADOPTED UPSTREAM · 51 CHECKS GREEN
2db9e37
Immutable Git SHA
TypeScript
Sdk
51 Checks Green
CI & Test Matrix
01 · Engineering problem
The failure mode
Claude Code Task subagents emit events carrying a non-null parent_tool_use_id, which leaked nested subagent token counts, tool calls, and partial stream deltas into parent-step accounting.
02 · Technical response
What changed
- 01Filtered subagent-originated assistant, user, tool-result, and partial stream events prior to parent-step normalization in Vercel AI SDK.
- 02Added 69 harness assertions verifying parent-step token and tool isolation.
03 · Verified outcome
Evidence-backed result
- ✓Passed 20/20 Vercel CI checks on commit 2db9e370e66b56e7802b30e7ea359d9dc9e27209 and adopted upstream with explicit credit to @patrickswedish.
04 · Cryptographic Git record
Immutable source evidence
Independent open-source engineering authored solely by Patrick Ribbsaeter (@patrickswedish). Company and project names identify the public repository context only under nominative fair use. No employment, client, vendor, or partnership relationship is implied unless explicitly stated.